1. Field of the Invention
The present invention relates to a vibrating mirror element, and more particularly, it relates to a vibrating mirror element including a driving portion.
2. Description of the Background Art
A vibrating mirror element including a driving portion is known in general, as disclosed in each of Japanese Patent Laying-Open Nos. 2005-333048 and 10-174462 (1998), Japanese Patent No. 4092283, Japanese Patent Laying-Open Nos. 2007-312465 and 2006-293116, Japanese Patent No. 3956933 and Japanese Patent Laying-Open No. 2007-10823, for example.
The aforementioned Japanese Patent Laying-Open No. 2005-333048 discloses an actuator including a driving arm supported by support portions on both end portions and so formed that the width thereof is reduced from both end portions toward a central portion in plan view and driving electrodes provided with piezoelectric layers and formed on the lower surfaces of both end portions of the driving arm respectively. In this actuator, the driving electrodes are so provided on both end portions of the driving arm as to ensure the areas of the driving electrodes while the width of the driving arm is reduced from both end portions toward the central portion so that the driving arm can be rendered easily deflectable in the vertical direction, whereby a driving region can be enlarged.
The aforementioned Japanese Patent Laying-Open No. 10-174462 discloses a piezoelectric conversion vibrator shaped into an isosceles triangle so that the width thereof is reduced from fixed ends fixed to stationary members toward a forward free end mounted with a weight and formed to have a constant thickness. This piezoelectric conversion vibrator is so formed that the maximum flexural stress on the fixed ends can be uniformly generated on the overall surface of the piezoelectric conversion vibrator, whereby a voltage generated in the piezoelectric conversion vibrator can be substantially doubled as compared with a case where the same has a constant width from the fixed ends toward the free end. Japanese Patent Laying-Open No. 10-174462 describes no deformed shape of the piezoelectric conversion vibrator so formed that the width thereof is reduced from the fixed ends toward the free end.
Each of the aforementioned Japanese Patent No. 4092283, Japanese Patent Laying-Open Nos. 2007-312465 and 2006-293116, Japanese Patent No. 3956933 and Japanese Patent Laying-Open No. 2007-10823 discloses a drive unit or the like including a mirror portion, a beam portion connected to the mirror portion and a driving portion connected with the beam portion and having a constant width in plan view.
When the actuator according to the aforementioned Japanese Patent Laying-Open No. 2005-333048 is applied to a vibrating mirror element, the vibrating mirror element may conceivably be so formed that a mirror portion is arranged on the central portion of the driving arm while the driving arm is vertically deflected to vary a position for reflecting light on the mirror portion. When the actuator according to the aforementioned Japanese Patent Laying-Open No. 2005-333048 is applied to the vibrating mirror element, however, the driving arm and the mirror portion may conceivably not be resonatable due to the driving electrodes directly provided on the lower surface of the driving arm. Therefore, the angle of inclination of the mirror portion may conceivably be disadvantageously reduced.
The aforementioned Japanese Patent Laying-Open No. 10-174462 describes no deformed shape of the piezoelectric conversion vibrator. When the piezoelectric conversion vibrator according to the aforementioned Japanese Patent Laying-Open No. 10-174462 is applied to a vibrating mirror element, therefore, the vibrating mirror element may conceivably be so formed that a mirror portion is arranged in place of the weight provided on the forward end portion of the piezoelectric conversion vibrator while the piezoelectric conversion vibrator is deformed by applying a voltage thereto. Thus, the mirror portion can be inclined by deformation of the piezoelectric conversion vibrator. When the piezoelectric conversion vibrator according to the aforementioned Japanese Patent Laying-Open No. 10-174462 is applied to the vibrating mirror element, however, the mirror portion may conceivably not be resonatable since the same is directly provided on the forward end portion of the piezoelectric conversion vibrator. Therefore, the angle of inclination of the mirror portion may conceivably be disadvantageously reduced.
In the drive unit or the like described in each of the aforementioned Japanese Patent No. 4092283, Japanese Patent Laying-Open Nos. 2007-312465 and 2006-293116, Japanese Patent No. 3956933 and Japanese Patent Laying-Open No. 2007-10823, the driving portion having the constant width in plan view may conceivably be mainly deformable only in the vertical direction. Therefore, no torsional deformation is caused on the driving portion, and hence the angle of inclination of the mirror portion is disadvantageously reduced.